The invention is in the field of lamp starter circuits, and relates more specifically to a simplified two-lead starter circuit for a gaseous discharge lamp.
Starter or ignition circuits for gaseous discharge lamps are generally well-known. For example, a basic starter circuit is shown in U.S. Pat. No. 3,917,976, while several more advanced starter circuits are shown in U.S. Pat. Nos. 4,275,337 and 4,695,771. While these starter circuits are generally satisfactory for their intended purpose, they suffer from a number of drawbacks. For example, these circuits typically require a tapped ballast or transformer winding, a sizable parts count and/or at least three external connections.
Some of these problems are overcome in U.S. Pat. No. 4,480,214, in which several embodiments of a fairly simple two-wire starter circuit are disclosed. Nevertheless, the starter circuits disclosed in U.S. Pat. No. 4,480,214 still hav a number of drawbacks. For example, these starter circuits require a minimum of five components, with a different circuit, requiring a sixth component (a choke coil) required for low-voltage operation. Additionally, because the secondary of the pulse transformer and a series capacitor are connected across the lamp, a failure in the capacitor (which is subject to a high starting voltage) would cause the secondary of the pulse transformer to be connected directly across the lamp, thus rendering it inoperative. Additional prior-art starter circuits are shown in U.S. Pat. Nos. 3,758,818 and 3,866,088.